Laser leveling instruments sweep a horizontal beam over the area. The instrument is adjusted by projecting the beam at a target located at least 10 meters away, preferably more since accuracy of the adjustment increases with distance to the target. It is convenient to reflect the beam back towards the vicinity of the instrument since it is easier for the technician to make readings, etc.
In the normal operating mode a laser leveling instrument is leveled in the X and Y axes and is used principally in that mode. When the instrument is used to establish a vertical plane (Z axis) it is tipped on its side so the (normally horizontal) beam will sweep in a vertical plane. The Z axis must be adjusted initially to a plane normal to the earth's surface. Normally the instruments are calibrated/adjusted in rooms having 3-4 meter ceilings which does not give enough room the locate a target far enough above the instrument to permit accurate adjustment.
This invention is directed to apparatus for enabling adjustment of the Z axis in laser instruments while using a target preferably located 10 or more meters from the instrument. A new adjustment method is used and takes less time than prior methods while giving excellent results.